Ozone and nitrogen dioxide may exert their toxic effects by peroxidation of the unsaturated fatty acids of the lung and other tissues. To test this hypothesis, mice will be fed chemically defined diets known to produce lung lipids having different rates of peroxidation. Diets will be deficient or sufficient in vitamin E or contain alpha-tocopheryl quinone or phenolic antioxidants. Animals will be exposed to ozone and nitrogen dioxide and the concentration and time required to obtain fifty percent mortality will be determined. The levels of ozone and nitrogen dioxide will be varied to provide differing rates of peroxidation. The effects of diet and oxidant stress upon potential detoxification enzymes will be examined. The turn-over of vitamin E in the lung and other tissues will be determined. These data will be used to assess the potential changes in the requirement of vitamin E and the useful indicators of oxidant damage. These studies are designed to test for putative toxic intermediaries, for a free radical mechanism of action of these air pollutants, and for protection against ambient air pollutants by dietary alterations and vitamin E supplementation. BIBLIOGRAPHIC REFERENCES: D. B. Menzel, R. J. Slaughter, A. M. Bryant and H. O. Jauregui. Prevention of Ozonide-Induced Heinz Bodies in Human Erythrocytes by Vitamin E. Arch. Environ. Health 30: 234-236, 1975. D. B. Menzel. "The Role of Free Radicals in the Toxicity of Air Pollutants (Nitrogen Oxides and Ozone)", in Free Radicals in Molecular Biology and Pathology, W. A. Pryor, Ed., Vo. II. Academic Press. 1976.